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I would guess that apart from the racing fraternity, most of us 'potterers' wouldn't comment on performance unless we considered we'd made a retrograde step. 'Adequate' is just that 
Fork Oil Grade
- Thread starter Staytite
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I read all of this a while ago and settled on Bel Ray 10w to use with my Lansdowne dampers. I find that this is very sensitive to under/over filling and that it uses very light damping settings on the adjusters. A Bell Ray 7 wt might be better.
Exactly as you say. It's only that I am about to fill some new forks that I started to over think it.
I went out yesterday on my working Commando when the sky was blue, but it was very cold. While
thinking about how my forks were operating it hailed hard then a partridge walked into the road and
stopped. Sh*t !
Should I go left or right of it ? Sh*t !
I was saved by a souped up 1 series BWM with black windows and fat alloys who came past me with
his (her?) 4 exhausts blazing like I was stood still. He/she hit the partridge and I passed through a shower
of feathers. Must have made a nasty mess of the front of his car.
But I lived to tell the tale and go back to contemplating grades of fork oil.
I went out yesterday on my working Commando when the sky was blue, but it was very cold. While
thinking about how my forks were operating it hailed hard then a partridge walked into the road and
stopped. Sh*t !
Should I go left or right of it ? Sh*t !
I was saved by a souped up 1 series BWM with black windows and fat alloys who came past me with
his (her?) 4 exhausts blazing like I was stood still. He/she hit the partridge and I passed through a shower
of feathers. Must have made a nasty mess of the front of his car.
But I lived to tell the tale and go back to contemplating grades of fork oil.
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- Jun 18, 2009
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- 106
Motul 15W fork oil, works well in my not-so-warm climate.
jbruney
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In addition: When mine came to me I've no clue what was in the forks so it was changed( milk drained out), and good old GTX 20w-50 installed - Front suspension operated like a rock, so changed to 10w-30. Didn't care for that either and moved to Type F ATF..... Slightly spongy, but has been good with a tad less stiction. ATF makes for quick recognition of failing seals which I think is a nice +. Memory fails but early on bought some crap at an HD dealer bottled as fork oil in late 79, I think, which was also a fail in this front end, but did well in the XLCR Showa forks.
- Joined
- Dec 28, 2008
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- 2,035
If you have matched the springs to your weight and have 20 to 25% sag with you aboard then I suggest that you beak-in the forks with a 15 weight oil. This will give you a sense of the damping and it is easier to increase viscosity then to decrease it.
Best.
Best.
Hi Road Scholar
Following the replies I've taken the decision to fill with Castrol 15W fork oil and a bottle arrived yesterday.
The reason for (over?) thinking the choice of oil is that in my experience draining the fork oil out through the
drain ports in the sliders is a pain and it is unlikely that all the oil comes out. The only sure way of getting all
the oil out is to remove each fork leg and turn upside down. Do other people have better solutions to drain
fork oil ?
I'd be interested in your reasoning for your comment "it is easier to increase the viscosity than decrease it"
My thinking is to try the 15W and if I want to increase or decrease the viscosity it is the same problem: drain
as much as possible out via the drain ports in the sliders knowing not all the fork oil will come out, measure
how much comes out and top up with either thicker or thinner grade. It seems the same issues to me to
increase or decrease the viscosity, or am I missing something?
Thanks
Following the replies I've taken the decision to fill with Castrol 15W fork oil and a bottle arrived yesterday.
The reason for (over?) thinking the choice of oil is that in my experience draining the fork oil out through the
drain ports in the sliders is a pain and it is unlikely that all the oil comes out. The only sure way of getting all
the oil out is to remove each fork leg and turn upside down. Do other people have better solutions to drain
fork oil ?
I'd be interested in your reasoning for your comment "it is easier to increase the viscosity than decrease it"
My thinking is to try the 15W and if I want to increase or decrease the viscosity it is the same problem: drain
as much as possible out via the drain ports in the sliders knowing not all the fork oil will come out, measure
how much comes out and top up with either thicker or thinner grade. It seems the same issues to me to
increase or decrease the viscosity, or am I missing something?
Thanks
Onder
VIP MEMBER
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- May 11, 2010
- Messages
- 4,264
Always pull the leg to drain so you can clean out the debris at the bottom.
That said, how much do you weigh? Has a lot to do with it.
With stock forks 15wt is about right. 10wt is plush but a bit soft for spirited
riding.
Warning: I weigh in a 9 stone full kit. My bike would seem a wallowing wheelbarrow
to most others.
That said, how much do you weigh? Has a lot to do with it.
With stock forks 15wt is about right. 10wt is plush but a bit soft for spirited
riding.
Warning: I weigh in a 9 stone full kit. My bike would seem a wallowing wheelbarrow
to most others.
- Joined
- Jan 31, 2010
- Messages
- 3,099
"
While
thinking about how my forks were operating it hailed hard then a partridge walked into the road and
stopped. Sh*t !
Should I go left or right of it ? Sh*t !"
Neither..."Buh Bump!"
While
thinking about how my forks were operating it hailed hard then a partridge walked into the road and
stopped. Sh*t !
Should I go left or right of it ? Sh*t !"
Neither..."Buh Bump!"
- Joined
- Dec 28, 2008
- Messages
- 2,035
Draining from the plugs is very easy, but takes time. Out the bike on its center stand, turn the forks to one of the stops such that the drain ,on the leg you start draining, is outer most and won't cover the brake and tire with oil, place a suitable container directly under the drain, remove the plug, adjust the catch pan as necessary and leave it. The oil will completely drain. I allow overnight. You can also make up a pair of tin cans with bridle and do both at the same time.
The amount of oil left in the legs will not be a factor if you are worried about overfilling. The Norton shop manual doesn't say a lick about removing the legs when changing fork oil. The 150 cc they call for has to assume a "wet" leg, and, in my experience, the Commando forks don't care if you are a tad high or low.
best.
DogT
VIP MEMBER
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- Jan 20, 2009
- Messages
- 7,394
I don't know, I found some SAE20 that I used. It came in a pint bottle so I bought a couple, Mind you I still have my original innards in the forks so I'm not obsessive about it.
Hi Olympus
I believe from your posts you recently fully rebuilt a Commando.
Which fork oil (make and grade please) did you use and do you like it?
Thanks
Just read your thread on the roll pin for the petrol tank cap. Very interesting as I’ve
to do that shortly and remember it being a big worry.
I believe from your posts you recently fully rebuilt a Commando.
Which fork oil (make and grade please) did you use and do you like it?
Thanks
Just read your thread on the roll pin for the petrol tank cap. Very interesting as I’ve
to do that shortly and remember it being a big worry.
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Most certainly..... I wish you the very best of luck
I've just looked at the tank I put a cap on 34 years ago and see I caused a couple of dints near the roll pin on the chrome of the cap.
But looks like I did not touch the Halfords black rattle can paint which has survived well modern petrol and pretty much all else for 34 years.
Hopefully I'll not batter the cap and do better this time.
Which straight 20W did you use ?
I've just looked at the tank I put a cap on 34 years ago and see I caused a couple of dints near the roll pin on the chrome of the cap.
But looks like I did not touch the Halfords black rattle can paint which has survived well modern petrol and pretty much all else for 34 years.
Hopefully I'll not batter the cap and do better this time.
Which straight 20W did you use ?
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